Due to the rapid development of optical technology, many display devices have been developed and applied to daily life. Among them, the rear projection display device has the advantage of large size display and high contrast, so it is regarded as an important development trend in the display. In general, the rear projection display device is that the viewer and the projector are located on both sides of the screen respectively, and the viewer views the image by the projection beam of the projector transmitted from the screen.
The architecture of the rear projection display device includes a projector and a projection screen. The projection screen includes a plurality of prism structures facing the viewer and a diffusion layer facing the projector, and each prism structure is provided with adjacent refractive portion and anti-light portion. The projection beam emitted by the projector is refracted and guided by the refractive portion of the prism structure, so that the viewer can see the normal image on the projection screen. The anti-light portion of the prism structure will absorb the majority of the external ambient light, so the external ambient light will not incident to the eyes of the viewer and cause the contrast of the image to decline, effectively prevent the external ambient light affect the image quality. In addition, the diffusion layer of the projection screen can homogenize the projection beam incident on the projection screen to help improve the quality of the image.
However, the architecture of the above-mentioned rear projection display device has the following drawbacks:
(1) Since the refractive portion and the anti-light portion are integrated on the same prism structure, so it can only be applied to the architecture of the hanging type projector.
(2) Since the refractive portion and the anti-light portion are integrated on the same prism structure, when the projection beam passes through the prism structure, a portion of the projected beam will be absorbed by the light absorbing material of the anti-light portion, resulting in the decrease in light utilization efficiency.
(3) When the above-mentioned structure of projection screen is used with the ultra short focus projector, the gain of luminance will be too low, and the uniformity of the image will be poor.
(4) Because the diffusion layer of the projection screen is facing the projector, the improvement of the image quality is limited, and there will be doubts of generating hotspots.
The information disclosed in this “BACKGROUND OF THE INVENTION” section is only for enhancement understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Furthermore, the information disclosed in this “BACKGROUND OF THE INVENTION” section does not mean that one or more problems to be solved by one or more embodiments of the invention were acknowledged by a person of ordinary skill in the art.